un‧chal‧lenge‧a‧ble /ʌnˈtʃæləndʒəbəl, ʌnˈtʃælɪndʒəbəl/ adjective
[Word Family: adjective: challenging, challenged ≠ unchallenged, unchallengeable; noun: challenge, challenger; verb: challenge; adverb: challengingly]

1. a belief, idea etc that is unchallengeable is definitely true and cannot be questioned or argued with:
unchallengeable evidence

2. if someone’s power or authority is unchallengeable, it cannot be taken from them

[TahlilGaran] Dictionary of Contemporary English ▲